The attached patch adds --with-ipv4-default only if use ipv6 is not enabled. If use ipv6 is enabled, you would expect ipv6 to be enabled by default. If ipv6 support breaks stuff for people that don't have ipv6 connectivity, it might have to be removed from make.defaults, but we should not disable ipv6 support of a program by default if use ipv6 is enabled, unless the ipv6 support is really broken.
Created attachment 1342 [details, diff] Enable --with-ipv4-default only if use ipv6 is not enabled
Changes added in a new ebuild revision. Thank you. - stroke